Oil scraping piston ring

ABSTRACT

An oil scraping piston ring which has a steel sheet strip having opposite projections formed longitudinally at one side thereof and projecting flatly at both sides and also having a plurality of slots formed equidistantly from each other at the same side and having the same shape. A plurality of slots are equidistantly formed at the other side of said ring and alternatively with respect to the opposing slots, and also having a plurality of curved edges which are alternatively bent in opposite directions. This piston ring is to be inserted into a piston groove for scraping oil and for readily removing to pass the oil.

limited States Patent [1 1 Minegishi OIL SCRAPING PISTON RING [75]Inventor:

[73] Assignee:

Hiroshi Minegishi, Kawagoe, Japan Nippon Piston Ring Co., Ltd., Tokyo,Japan [22] Filed: Dec. 29, 1970 [21] Appl. No.: 102,491

[ Foreign Application Priority Data [56] References Cited UNITED STATESPATENTS 2,670,256 2/1954 Hsia-si Pien 277/139 3,353,830 11/1967 Bell277/139 [111 3,736,666 June 12, 1973 Attorney-Sughrue, Rothwell, Mion,Zinn & Macpeak 5 7] ABSTRACT An oil scraping piston ring which has asteel sheet strip having opposite projections formed longitudinally atone side thereof and projecting flatly at both sides and also having aplurality of slots formed equidistantly from each other at the same sideand having the same shape. A plurality of slots are equidistantly formedat the other side of said ring and alternatively with respect to theopposing slots, and also having a plurality of curved edges which arealternatively bent in opposite directions. This piston ring is to beinserted into a piston groove for scraping oil and for readily removingto pass the oil.

1 Claim, 5 Drawing Figures PATENTED inn mm FIG. I

FIG. 4

INVENTOR HIROSHI MINEGISHI ATTORNEY? FIG. 5

a l OIL SCRAPING PISTON RING BACKGROUND OF THE INVENTION 1. Field of theInvention DESCRIPTION OF THE PREFERRED EMBODIMENT Reference is now madeto the drawings, which show This invention relates to an oil scrapingpiston ring one embodiment of the present invention, and particufor apiston of an internal combustion engine, and more particularly to an oilscraping ring adapted for obtaining good oil scraping of the piston andhaving high tensile strength upon insertion into the piston groove andplacing the piston in the engine.

1. Description of the Prior Art The conventional channel type of pistonring known as a high strength, high followability piston ring cannot beused for small diameter pistons having piston ring grooves which arenarrow in axial width, for example, less than 3.5 mm, because of itssmall size. For this reason, cast iron oil scraping rings are used forsuch types of pistons. Consequently, the ring does not have enoughstrength, due to its narrow axial width, thus causing insufficientfollowability. Since this type of ring was complemented by usingexpensive high strength material, it is not economical. In addition,several oil windows formed in the piston ring must be .reduced in sizeand number due to the weakness of the ring at the point of strength ofthe material, thereby causing worse oil passing characteristics.

SUMMARY OF THE INVENTION This invention contemplates elimination of theaforementioned disadvantages of the conventional oil scraping pistonring of small diameters and provision of a novel and improved oilscraping piston ring which may have high tensile strength and good oilpassing characteristics.

It is one object of the present invention to provide an oil scrapingpiston ring which is small and strong enough for small diameter pistonsof compact engines.

According to one aspect of the present invention, there is provided anoil scraping ring which comprises a steel sheet strip having oppositeprojections formed longitudinally on one side thereof and projectingflatly on both sides and also having a plurality of slots equidistantlyformed on the same side in the same shape and also having a plurality ofslots equidistantly formed at the other side and alternatively withrespect to the opposite slots and having a plurality of curved edgesalternatively bent in opposite directions.

The other objects, features and advantages of the present invention willbecome apparent from the following description taken in conjunction withthe accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of theoriginal'material formed and cut with slots for manufacturingthe oilscraping piston ring of this invention;

FIG. 2 is a longitudinal sectional view of the material shown in FIG. 1taken along the line 11-11 therein;

FIG. 3 is a perspective view of part of the oil scraping piston ring ofthis invention;

FIG. 4 is a partial transverse sectional view of the oil scraping pistonring which is inserted into the piston groove; and

FIG. 5 is a transverse side sectional view of part of the conventionalcast iron oil scraping piston ring used for the same purpose as thisinvention.

larly to FIG. 1, which shows the original material formed and cut withslots for manufacturing the oil scraping piston ring of this invention.A steel sheet strip 1 has opposite projections 2 and 2' formedlongitudinally on one side thereof and projecting flatly from both sidesabove and below the sheet, and also includes a flat portion 3 shown inFIGS. 1 and 2 so that a T- shape cross-section is formed. Thelongitudinally projecting side of the sheet strip 1 is formed to have aplurality of slots 4 formed equidistantly from each other and in thesame shape, such as a rectangular shape. The other flat side of thesheet strip 1 is also formed or cut to have a plurality of slots 5formed equidistantly from each other and alternatively with respect tothe opposite projected side of slots 4. The flat edge 3 of the sheetstrip 1 is bent alternatively in opposite directions such as in anupward and downward direction at a pre determined line m-m shown in FIG.1 so that the respective edges of the flat portion 3 of the sheet strip1 are alternatively bent upwardly and downwardly at approximatelydegrees to form curved projections or edges 6 and 6'. The thus formedstrip 1 is bent into a circular shape having a gap at one portion sothat the bent projections or edges are disposed inside of the circle asshown in FIG. 3 to form an expander. This expander is inserted into apiston ring groove g of a piston 8 as shown in FIG. 4, together withupper and lower thin rings 7 and 7 placed above and beneath the expanderin combination therewith.

In operation of the thus constructed expander inserted into the pistonring groove g, the bent edges or projections 6 and 6' urge the flatcircular rings 7 and 7' peripherally outwardly. Accordingly, when thisexpander is inserted into the piston ring groove of the piston insertedinto a cylinder 9, the flat rings 7 and 7 are so urged by the bent edges6 and 6' of the expander in a radially outward direction as to closelycontact the inner wall of the cylinder 9 to properly scrape the oiltherefrom. The scraped oil is then removed through a plurality of oilpassages or gaps l0 and 104 to flow through the oil holes 11 formed inthe piston.

If the material of the expander is made of high strength material, suchas l7-7PH stainless steel, the mechanical strength of the expander isincreased to improve the resiliency of the expander itself. Thiseliminates problems caused by an accidental defect in the scrapingpiston ring and raises the surface pressure of the flat rings againstthe inner surface of the cylinder 9. If chromium is plated onto thescraping ring, the contacting portions of the ring hardly wear andlessen the oil flowing resistance to improve the oil passingcharacteristics of the scraping ring.

It should be understood from the foregoing description that since theoil scraping piston ring has a smaller axial width with flat smallprojections 2 and 2' combined with the flat rings 7 and 7 above andbeneath the ring 1, a small axial width oil scraping piston ring adaptedfor compact engines is provided. Thus, the scraping piston ringaccording to the present invention will have enough strength even whenused with pistons smaller than 3.5 mm in axial width in comparison withthe conventional cast iron piston ring.

, It should also be understood that the oil scraping piston ring of thisinvention is formed integrally by bending at one side onlylongitudinally along the strip, and accordingly it provides very hightensile strength to properly scrape the oil and to smoothly pass the oilthrough the gap formed between the piston ring and flat rings into theoil hole.

It should also be understood that since the scraping piston ring of thisinvention is simple in structure and manufacture, it may be produced inmass production by a less expensive process.

I claim:

1. A piston ring assembly for an internal combustion engine comprising apair of flat annular rings and an expander member disposed intermediatesaid ring, said expander member comprising a flat annular washertypesteel strip having a radial dimension greater than the axial dimensionand flat projections protruding from opposite surfaces of said stripalong one edge thereof, a plurality of first transverse slots extendinginto said strip from said one edge and a plurality of second transverseslots extending into said strip from the other edge thereof alternatelywith respect to said first slot, adjacent portions of said other edgebeing bent in opposite directions into engagement with the radial inneredges of said flat annular rings to force said rings in a radiallyoutward direction while permitting oil to flow between said rings.

1. A piston ring assembly for an internal combustion engine comprising apair of flat annular rings and an expander member disposed intermediatesaid ring, said expander member comprising a flat annular washer-typesteel strip having a radial dimension greater than the axial dimensionand flat projections protruding from opposite surfaces of said stripalong one edge thereof, a plurality of first transverse slots extendinginto said strip from said one edge and a plurality of second transverseslots extending into said strip from the other edge thereof alternatelywith respect to said first slot, adjacent portions of said other edgebeing bent in opposite directions into engagement with the radial inneredges of said flat annular rings to force said rings in a radiallyoutward direction while permitting oil to flow between said rings.